Important Factors to Consider when Purchasing Wigs for women A number of factors determine the cost of hair wigs. Human hair wigs are most expensive, although some are made of synthetic materials. The natural human hair combs are also among the most costly. Although they're generally less expensive but require more attention. Hair bobs react differently to humid conditions and the weather , and could need to be styled or dyed to make it look the best. In light of this it is important to consider whether the expense of a natural human hair bob is worth the extra cost.